Control system



June 14, m J, F, TRITLE 2,12%,9555

CONTROL SYSTEM Filed March 1'7, 193'! 5 Sheets-Sheet; l

I RUN 5W OFF Inventor: John F Tri'tle,

Attorney SERVICE Iiifa June 14, 1938. TRlTLE I 2,120,956

CONTROL SYSTEM Filed M arch 17, 1937 3 Sheets-Sheet 2 lrfiventor: John F? Tritle,

' His Attorney.

June 14, 1938.. J. F. TRITLE 9 3 CONTROL SYSTEM Filed March 17, 1957 3 Sheets-Sheet-E as 2a- 45 g 57 Inventor":

John F" Tritle,

b 7v '5, W 9 7 I-l IS- At torneg.

Patented June 14, 1938 I UNITED STATES rmsnr crrica 2,120,956 demon srsrsm John F. Tritle, Erie, Pin, assignor to General Electric Company, a corporation of New York Application March 17, rear, Serial No. 131,391-

23 Claims. (cl. ire-its) My invention relates to control systems, more controller in accordance with the current flowparticularly to motor control systems for elecmg in the motor circuit. tric vehicles, and has for an object the provision In order to provide for uniformly smooth of a simple, reliable, and inexpensive control sysbraking of the electric vehicle over a wide range 5 tern of thischaracter. of speeds, the controller, which operates through 5 Various motor control systems have heretofore two trips during acceleration of the vehicle, is been proposed for propelling and braking elecarranged to operate through four trips progrestric vehicles. While many of such systems have sively to exclude the braking resistors. been to a large extent satisfactory in the past, For a more complete understanding of my inl0 the constantly increasing demands of metropolivention, reference should now be had tothe drawtan trafllc conditions, together with the higher ings in which Fig. 1 is a somewhat diagramstandards of passenger comfort, necessitated by matic illustration of a control system embodying competition with other vehicles, such for exammy invention; Figs. 2. to 6 inclusive are simplified ple as gasoline driven busses, leaves much to be circuit diagrams illustrating various stages in the desired in the operatingschedules provided by accelerating operation of the vehicle; and Figs. 7 15 such prior control systems. to 12 inclusive are similar simplified circuit dia- In order to meet these modern demands, it is grams illustrating the braking operation. necessary to accelerate quickly and smoothly to Referring now to the drawings, I have shown high speeds, for example at accelerating rates my invention as embodied in a control system for of the order of 2 to 4% miles per hour per seca plurality of traction motors ID to Hi inclusive 2!) end, and to decelerate smoothly at equal or having series field windings M to I! respectively. greater rates. Such high rates of acceleration and As shown, the principal operating elements and deceleration furthermore, must be accomplished devices incorporated in the improved control'syswithout subjecting the passengers to shocks or tern shown comprise a plurality of motor conjars due to sudden changes in the torque or the trolling resistors i8, i9, 2B, 2!, and 22; field shunt- 25 braking eiIort and because of the high speeds ining means 23; a fluid pressure operating device volved, extreme reliability is required. Accord- M for driving a controller 25 associated with the lngly, it is a further object of my invention to resistor i8; a cam switch 26 also driven by the provide a simple and highly reliable motor 0011- operating device 24; an acceleratin and decel- 0 trol system for quickly and smoothly accelerating crating relay 2'! for controlling the speed of opand decelerating an electric vehicle. eration of the field shunting means 23 and the [In carrying out my invention in one form, I operating device 24 in accordance with the motor provide a traction motor and a plurality of motor current; and master control means including a controlling resistors for connection in circuit master accelerating controller 28 and a master a therewith, together with a controller, associated braking controller 29, In addition, the control with a first one of the resistors, arranged for forsystem includes a pair of line circuit breakers ward and reverse operation progressively to ex- 30 and ii for connecting the motors to a source clude the first resistor from the motor circuit. of energy represented by a trolley 32 and 9, Associated with the resistor controller, I provide ground connection 33; a braking switch 34 having transfer means operable upon exclusion of the a plurality of main contacts 35, 3t, and 31 for first resistor during forward operation of the con connecting the motors in a dynamic braking troller for quickly excluding another resistor and circuit with the motor controlling resistors; a reinserting the first resistor in the motor'circuit cushioning contactor 38 for controlling the refor exclusion a second time upon reverse operasister 20; a transfer switch 38 which cooperates tlon 01 the ntroller. with the controller 25 to control the resistors I8 45 More specifically, I provide a fluid operating and i9, and a spotting relay 40 for controlling device for the controller having opposed reciprothe operation of the operating device 24, the eating pistons for operating the controller in cushioning contactor 38, and the transfer means corresponding directions and timing means for 39 during coasting to predetermine the amount of controlling the speed of the controller in both resistance initially included in the braking i 50 directions, the timing means comprising'a body cuit in accordance with the speed of operation of incompressible liquid communicating with one of the vehicle. of the pistons through a restricted orifice and It is believed that a complete understanding means for selectively controlling the orifice to of my invention may best be had from a descripstop the controller or to increase the speed of the I tion of the operation and accordingly certain of 55 the operating devices and elements will first be briefly described.

- The field shunting means 23, as shown, comprises a multiple contact, pressure-operated switch for progressively shunting the motor fields. This pressure operated switch comprises a casing 4| having a flexible diaphragm 42 for controlling a plunger 43 which is normally biased to its uppermost position by a spring 44. Fluid pressure is supplied to the upper side 0! the diaphragm 42 from a suitable source of pressure through an electrically controlled valve 45 which is normally biased to the position shown to connect the upper side of the diaphragm to atmosphere through a passageway 45, the upper port of the valve 45, and the passageways 41 and 48. When the energizing winding of the valve 45 is energized, the valve is operated to its lowermost position to connect the upper side of the diaphragm to a suitable source of fluid pressure through the passageway 45, the lower port of the valve 55 and the supply conduit 49, and the plunger 55 is thereupon moved downwardly against the bias of the spring 4i.

Mounted on the lower end of the plunger d5 I provide a pair of conducting segments 55 and 51 arranged normally to engage cooperating sets 01' fixed contacts 52 and 53 respectively. As shown, the contacts 52 in cooperation with the conducting segment 55 control a shunt circuit for the field windings l5 and 11, which shunt circuit includes a tapped resistor 54 and a reactor 55. Similarly, the contacts 55 and the conducting segment 5! control a shunt circuit for the field windings l4 and 15, which shunt circuit includes a tapped resistor 55 and a reactor 51. With the conducting segments 50 and 51 in the normal position shown, the field windings are completely shunted, only the reactors 55 and 51 being included in the shunt circuits. As the conducting segments 50 and 5! are moved downwardly upon the application of pressure to the diaphragm 42, the resistance of the shunt circuits is gradually increased by the sequential opening of the contacts 52 and 53, the final movement of the segments 55 and 51 completely interrupting the shunt circuits.

As will be explained more fully hereinafter, it is sometimes desirable to control the rate at which the fields are shunted and accordingly an electrically operated plug valve 55 is provided tor plugging'the exhaust passageway 48 to con trol the rate at which pressure is exhausted from the upper side of the diaphragm 42 when the valve 45 is deenergized. The rate at which pressure will be exhausted from the upper side or the dfi'phragm with the plug valve 58 closed may initially be set by means of a needle valve 55 interposed in a second exhaust passage 55.

The controller 25 illustrated diagrammatically as comprising a movable brush arm 51 mounted on a rotatable shaft 52 may be of any desired type, but is preferably of the commutator type described and shown in my cop-ending. application Serial No. 22,745, filed May 22, 1935, entitled Control systems, which application is assigned to the same assignee as the present invention. As is fully described in my above rel-erred to application, controllers of this type CDIIIIIBIiSE a large number of commutator bars over which suitable brush arms move to vary in small increments a resistor connected to the commutator bars... While any desired number of commutator bars may be provided, I have found it desirable in one embodiment of my invention to utilize 130 such bars in order to vary in small steps the associated resistor.

As shown, the driving shaft 52 is connected through suitable gearing to an intermediate shaft 53 which is in turn connected to the operating shaft 84 of the fluid operating device 24. This operating device 24 is provided with opposing pistons 55 and 55 reciprocating within a cylinder casing 5'1 and connected, as shown, by means of a suitable rack and pinion to the operating shaft 54. Operating fluid pressure issupplied from a suitable source, not shown, through a supply pipe 55, and is controlled by a pair of double-acting valves 59 and 15 which are interconnected for operation by a single operating winding H, the valves being biased to the position shown by means of a spring I2. Adjacent the cylinder casing 61 I provide a timing chamber 13 within which is a body of incompressible liquid '14, such for example as oil, which body communicates with the lower side of piston 55 through suitable conduits l5 and i5 and a restricted orifice controlled by a valve 'l'i.

Thus, when the operating winding ii is deenerglzed, pressure is admitted directly from the supply pipe 58 through a conduit '15 to the piston 55, so as to force the reciprocating pistons downwardly to the position shown, the movable arm 51 of the controller 25 being thus operated to the position indicated by the letter A in the drawings. Likewise, when the operating winding H is energized, the valves 55 and 15 are reversed so that the fluid pressure on the piston 55 is exhausted to atmosphere through the right-hand port of the valve 59, and fluid pressure is admitted through the left-hand port of the valve 10 and a conduit 19 to the timing chamber '13. The incompressible liquid 14 is thus forced through the conduits i5 and 16 and the restricted orifice controlled by the valve T1 to operate the piston 58 upwardly and move the brush arm 51 of the controller 25 in a left-hand direction from position A toward position B.

It will be apparent, therefore, that the speed at which the reciprocating pistons 55 and 55 move in either direction depends upon the amount of restriction interposed by the valve TI to the flow of the incompressible liquid through the conduits '15 and T6. Normally, this valve is biased to the partially open position, shown, by a spring 85, in which position the upper end of the valve stem engages a stop pin 81 which is normally biased to the position shown by the spring 52. The valve H is provided with an energizing Wind ing or stop coil 53 and the stop pin 81 is controlled by a similar energizing winding or speed coil 84. Thus when the winding 83 is energized, the valve 11 is moved downwardly against the bias of the spring 85 to close the conduit "16 so to stop the movement of the pistons 65 and 66 by preventing the flow oi the incompressible liquid M through the conduit. When both of the windings 83 and 54 are deenerglzed, the pistons operate at 1101'" mai or low speed the flow of fluid being restricted by the valve glued to retract the stop pin ill, the valve ll is opened further by the spring 55 to increase the size of the flow controlling orifice in the conduit l5 and thus provide for high speed operation oi" the pistons Eli and 5t.

Mounted on the intermediate shaft 53 for movement with the brush arm iii of the controller 25 is the cam switch 25 which is provided with a plurality of pairs of contacts 85, 8B, 51, and 88 arranged to be operated between open and closed ill and when the winding B l is enervided with a plurality of cam switches III to I20 circuit positions by a plurality of associated cams. This cam switch 28 is also provided with a cam 89 for controlling a pivoted arm 90, the outer end of which supports a-contact 9I in cooperating relation with a contact 92 carried by the pivoted armature 93 of the spotting relay 0.

Normally, the pivoted armature 93 is biased for movement in a clockwise direction about its pivot to separate the contacts 9| and 92, the amount of separation of the contacts 9i and 92, being determined by a cam disk 9| which is provided with a plurality of cam surfaces 95, 98

- and 91 for engaging a conducting finger 98 carried by the armature 93, the cam suriaces 95 and 91 comprising conducting segments for a purpose to be more fully described hereinafter. This cam disk 94 is normally biased by a spring 99 to the position shown and is provided with an operating winding I00 which is connected across two of the motor fields, as will be more fully described hereinafter, to operate the cam disk from its biased position in accordance with the speed of the motors. As shown, the cam disk 94 is also provided with a ratchet IOI arranged to be engaged by a spring-pressed latch I02 whenever the winding I03 associated with the armature 93 is deenergized. When the winding I03 is energized, the latch I02 releases the cam disk 94 for movement in accordance with the speed of the motors and as soon as the winding I03 is deenergized, the cam disk 94 is latched in the position it then occupies, one of the cam surfaces 95, 98, or 91 then serving to limit the clockwise movement of the armature 93 so as to determine the amount which the contacts 9i. and 92 will be separated. These contacts 9i and 92 control the stop coil 83 of the operating device 24 in a manner to be more fully described hereinafter and accordingly the cam switch 26 operates in a direction to move the contact 9I toward contact 92 until the contacts are engaged, whereupon the stop coil 83 is energized to stop the operating device 24, the controller 25, and the cam switch 28.

The accelerating relay 21 which controls the speed of operation of the operating device 24 and the field shunting means 23 under certain conditions is mounted adjacent the master controller 28 and the braking controller 29 and comprises a movable armature or core I04 for operating a pivoted contact member I05 having cooperating front and back contacts I06 and I01 respectively. The contact member I05 is normally biased into engagement with the front contact I08 by a spring I98 and the armature I04 is provided with a pair of series windings I09 and H0, the winding I09 being connected in the braking circuit and the winding IIO being connected in the accelerating circuit. In addition, the armature I04 is provided with a shunt winding II I, the energization of which is controlled by the back contact I01 in a manner to be more fully described hereinafter. The current setting of the accelerating and decelerating relay 2'! is determined by the spring I08, one end of which is connected to a pair of pivoted adjusting arms H2 and N3, the arm II2 being arranged to engage a cam III carried by the braking controller 29, while'the arm II3 engages a cam I I5 carried by the master accelerating controller 28. Thus, it will be seen that upon movement of either of the controllers 28 or 29 from their off positions, the spring I08 will be stressed to increase the current setting of the relay 21,

As shown, the accelerating controller 28 is proinclusive arranged for operation by a plurality 01. corresponding cams and the braking controller 29 is provided with a plurality of cam switches I2I to I28 inclusive arranged for operation by suitable corresponding cams. The master accelerating controller 28 is movable from an oil. position through a switching position and a plurality of running p sitions and the braking controller 29 is movable from an off position through a plurality of service positions, the two controllers when in their respective off positions providing for a coasting operation of the vehicle.

The sequence of operations by means of which the electric vehicle is quickly and smoothly accelerated and decelerated will first be described in general and the detailed circuits utilized in accomplishing this sequence of operation will then be traced.

In order initially to apply power to the traction motors for accelerating the vehicle, the line circuit breakers 30 and 3i are closed to connect the motors to the source of energy with the fields shunted. The energizing circuit thus established for the motors may be traced from the trolley 32 through the contacts of the line breaker 30, and a conductor I21 to a common connection point I28. At this common connection point the current divides, part flowing through a conductor I29, the armatures of the motors I3 and I2, a conductor I30, the field windings I6 and IT, and by way of a conductor I3I to a second common connection point I32, while the other part of the current flows from the common connection point I28 through a conductor I33, the field windings I4 and I5, a conductor I34, the armatures of the motors I I and I0, and by way of a conductor I35 to the common connection point I32. From thi'. common connection point I32, the current flows through a conductor I35, the contacts of the line breaker 3|, a conductor I3'I, the resistor 20, a conductor I38, the lower contacts of the transfer switch 39, the resistors I9 and I8, the movable brush arm 6| of the controller 25, the conductors I39 and H0, and by way of the series winding IIO on the accelerating relay 21 to the ground connection 33. The circuits thus established are shown best in Fig. 2 and it will be apparent that the traction motors are permanently connected in a parallel bridge circuit with two motors connected in each arm of the bridge between the common connection points I28 and I32.

The next step in accelerating the motors is accomplished by energizing the field shunting means 23 to remove the shunts from the field windings of the motors to increase the field excitation and thereby further accelerate the motors. As soon as the motor fields are completely unshunted, the cushioning contactor 3i is energized quickly to exclude the resistor 20 from the motor circuit, whereupon the operating device 24 is energized for movement from its A position to-- ward its B position progressively to exclude the resistor I9. In Fig. 3, I have shown the circuits established at the instant the brush arm SI of the controller 21 completes its movement.

Immediately upon movement of the brush arm 6I to its B position, the transfer switch 39 is energized to exclude the resistor I9 from the motor circuit and to reinsert the resistor I8, the circuit from the transfer switch now extending through a conductor Ill which is connected to the opposite end of the resistor I8. The circuit thus established is shown in Fig. 4 and the brush arm 8| immediately begins to move in a right-hand direction towards its A position progressively to exclude the resistor I8 a second time. In Fig. 5 the accelerating circuits are shown with all of the resistors excluded from the motor circuit and the final accelerating step is then accomplished by deenergizing the field shunting means 23 again to shunt the field windings, of the motors, the final accelerating circuit connections being shown in Fig. 6.

Thus, it will be seen that the resistors I8 and I8 are progressively excluded from the motor circuit by operating the brush arm BI of the controller through two trips between its A and B positions and by substituting the resistor I0 for the fixed resistor I9 at the end 01' the first trip of the brush arm BI. It will be understood of course that the speed at which the brush arm BI oper" ates between its A and B positions, as well as the speed at which the field shunting means operates to shunt the fields at the end of the accelerating operation, is controlled by the accelerating relay 21 in a manner to be more fully described hereinafter so as to maintain a substantially constant accelerating current throughout the entire accelerating operation,

In describing the braking operation, it will be assumed that the vehicle is operating at a high rate of speed, say for example 40 miles per hour, so that the spotting relay 40 occupies the position shown in Fig. 1. In order to go from motoring operation to braking operation, the master controller 28 is moved from its running position to its off position, whereupon the vehicle will coast until such time as the braking controller 29 is operated to its service position.

As soon as the master controller 28 is operated to its off position, the line breakers 30 and 3i are deenergized to disconnect the motors from the source of energy and the braking switch 34 is energized to close its contacts 35, 35, and iii and thereby connect the resistors I8, I9, 20, 2 I, and 22 in circuit with the motors for braking operation. Closure of the contacts 36 is effective to connect the resistor 22 across the two common connection points I28 and I32, the circuit extending from the connection point I28 through a conductor I42, the contacts 36, the resistor 22, and by way of the conductors I43 and I36 to the common connection point I32.

Closure of the contacts 35 and 31 is eii'ective to connect the resistors IB, I9, 20, and 2i in a braking circuit which extends between the midpoints of the two opposite arms of the parallel bridge circuit in which the motors are permanently connected. This braking circuit extends from the conductor I30 which connects the armature of the motor I2 to the field winding I6 through a conductor I44, the contacts 35, a conductor I45, the conductor I31, the resistor 20, the lower contacts of the transfer switch 39, the resistors I9 and IB, the movable brush arm SI of the controller 25, the conductor I39, the series winding I09 on the relay 21, the conductor I46, the resistor 2 I, a conductor I41, the braking contacts 31, and by way of a conductor I48 to the conductor I34 connecting the armature of the motor II to the field winding I5.

Thus, it will be seen that the resistors I8, I9, 20, and 2I are connected across two terminals of the bridge circuit, while the resistor 22 is connected across two other terminals of the bridge circuit. These connections are shown best in Fig. 7. I have found that by so connecting the resistor 22, automatic field shunting of the motors is provided during dynamic braking. The shunting efi'ect oi this resistor 22 "varies as the voltage across the motor armatures which voltage depends upon the speed, so that at high speeds, approximately 40 miles per hour, only about 40% oi the total braking current flows through the motor fields, while at low speeds of approximately 5 miles per hour, the current through the series fields reaches a maximum oi about of the total brake current. By means of this automatic field shunting arrangement, the motor voltages developed during braking are reduced and the control of the braking operation is considerably simplified.

vIn addition to the above described circuits, operation of the master control means to its coasting position energizes a field flashing contactor I49 so as to connect a battery I50 across two of the motor fields to ensure quick build-up of the braking current. As shown, one side oi the battery I50 is connected directly to ground and the flashing circuit for the field windings may be traced from the other side of the battery through the contacts of the field flashing contactor I49, a current limiting resistor I5I, the conductor I21, the field windings I4 and I5, the conductors I34 and I48, the braking contacts 31, the conductor I41, the resistor 2I, the conductor I45, the series winding I09 on the relay 2], the conductor I40, and by way oi the series winding I ill on the relay 2? to the ground connection 23.

Thus, it will be seen that the traction motors are connected in a closed dynamic braking circuit with the fields flashed and the motors would, of course, build up to initiate braking were it not for the fact that the fields are shunted, as shown in Fig. 7, by the field shunting means 23. In order to initiate braking now, it is necessary only to move the braking controller 29 to its braking position so as to energize the field shunting means 23 and thereby unshunt the field windings of the motor. The braking current thereupon quickly builds up to an eiicctive value and the brush arm 6| of the controller 25 begins to move from its A position toward its B position to exclude the resister I8 from the braking circuit. As soon as the brush arm SI reaches the position shown in Fig. 8, the transfer switch 39 is energized to open its lower contact and close its upper contact, thereby to exclude the resistor I0 and reinsert the resistor I8, as shown in Fig. 9.

As described above in connection with the accelerating operation, the brush arm SI immediately begins to move in a reverse direction toward its A position progressively to exclude the resistor I8 from the braking circuit a second time. will be observed that during these first two trips of the brush arm BI, the resistor 20 is connected in the braking circuit. As soon as the arm BI returns to its A position,.the transfer switch 39 is deenergized to open its upper contacts and close its lower contacts and the cushioning contactor 38 immediately operates to exclude the resistor 20. Thus, the circuit connections shown in Fig. 10 are established, the resistors I8 and I9 again being connected in the braking circuit.

The brush arm BI is now again moved In a lefthand direction toward its B position to exclude the resistor I8 9. third time and the transfer switch is energized at the conclusion of this trip, as described above, to exclude the resistor I! and reinsert the resistor I8 (see Fig. 11) whereupon the brush arm GI again returns to its A position progressively to exclude the resistor I8 from the braking circuit a fourth time. It will be understood, of course, that the movement of the brush arm BI during the braking operation is controlled by the relay 21, the series winding I88 being connected at all times in the braking circuit so as to maintain a constant braking current as the vehicle slows down. In the final braking position shown in Fig. 12, all the resistance is excluded from the circuit except the resistor 2I.

Referring now to Fig. 1, in which all of the control devices are shown in their deenergized positions, the circuit connections for accomplishing the above described sequence of operations will be described in detail. In order initially to energize the control circuits preparatory to acceleration of the vehicle, it is necessary first to close a control switch I52 which connects the control apparatus to a suitable source of control energy. In order to simplify the drawings, this source of control energy has been indicated by conventional plus and minus signs.

Since the master controller 28 and the braking controller 28 are in their respective ofi posl tions corresponding tocoasting operation, clo sure of the control switch I52 completes energizing circuits for the braking switch 34 and the field flashing contactor I48 to establish the coasting circuits shown in Fig. 7. The energizing circuit for the braking switch 34may be traced from the positive source of control energy through the control switch M2, the conductors I53 and E58, the contacts M8 which are closed when the master controller 28 is in its off position, the conductor I185, the interlock contacts I56 on the line breaker 38, the conductor I51, the interlock contacts are on the line breaker 3i, the conductors I58, toil, and MM, and by way of the energizing winding for the braking switch 84 to the negative source of control energy. The energizing circuit for the field flashing contactor errtends from the intersection of the conductors E88 and Iti through the winding of the field flashing contactor to the negative source of control energy.

Simultaneously, an energizing circuit for the operating winding ll of the operating device 281s established to operate the valves 69 and I8 to a position in which pressure is applied to the timing chamber ill. The operating device 28 does not move so as to cause operation of the controller 25 since an energizing circuit is simultaneously established for the stop coil 88 of the device 28. The energizing circuit for the operating winding Ii extends from the intersection of the previously energized conductors I58 and I68 through a con ductor H82, a pair or interlock contacts I63 and I88 on the braking switch 88, the conductors I85, E88, it'l, and 988, a pair of interlock contacts I68 on the transfer switch 38, and by way of the conductors H8 and I'll through the winding l! ,to the negative source of control potential. Similarly, the energizing circuit for the stop coil 88 extends from the previously referred to interlock contact 183 on the braking switch Nthrough a similar interlock contact N2, the conductor Iltl, the normally closed contacts I22 on the braking controller 28, the conductor I14, the contacts 89 and 82 of the spotting relay 48 and by way of conductors Ilii and H6 through the stop coil 83 to the negative source of control energy.

In order now to connect the motors to the main source of energy for acceleration, the master controller 28 is operated from its off position to its switching position to open the associated contacts II8 and to close the contacts H6 and H1. Opening of the contacts IIB of course deenergizes the braking switch 34 and the field flashing contactor I49, while closure of the contacts II! and H1 establishes energizing circuits for the line breakers 38 and 3| to connect the motors in the accelerating circuit shown in Fig. 2.

The energizing circuit for the line breaker 38 may betraced from the positive source oi control energy through the control switch I52, the conductors I53, I11 and I18, the normally closed contacts I26 on the braking controller 29, the conductor I19, the contacts IIS on the master controller 28, the conductor I88, the interlock contacts IN on the braking switch 34. the conductor I82, the energizing winding of the line breaker 38, the conductors I88 and I84, and through the contacts 81 on the cam switch 26 to the negative source of control energy. It will of course beapparent that these contacts 81 on the cam switch 26 are closed so long as the cam switch 28 is in its A position. As soon as the line breaker 88 closes, a self holding circuit is established which extends from the intersection oi the conductors I83 and I 84 through a conductor H85 and the interlock contacts I86 on the line breaker 38 to the negative source of control energy. This holding circuit by-passes the contacts 8'5 on the cam switch 28 so as to maintain the line breaker 38 energized even though the cam switch 28 and the controller 25 are operated from their respective A positions.

Similarly, the energizing circuit for the line breaker 88 may be traced from the positive source of control energy through the control switch 682, the conductors I53, I'll, and I81, the normally closed contacts 625 on the braking controller the conductor B88, the contacts M1 on the master controller 88 and by way of the conductors E88 and H88 to the operating winding of the line breaker 8i and the negative source oi control energy.

Upon closure of the line breakers 38 and M, the motors are connected in the energizing circuit shown in Fig. 2 and begin to accelerate with the field windings shunted. Closure of the line breaker iii, moreover, is eflective to complete a circuit for energizing the operating valve of the field shunting means 23. Thus pressure is applied to the upper side of the diaphragm 88 and the conducting segments 58 and 5| move downwardly progressively to unshunt the field windings. This energizing circuit for the valve 48 may be traced from the intersection or the previously energized conductors I88 and I98 through the interlock contacts ISI on the line breaker 8!, the conductors E92 and I88, the interlccls contacts B88 on the transfer switch 38 and by way of conductors I85 and I96 through the energizing winding for the valve 45 to the negative source of control energy.

In order further to accelerate the motors after the field shunts have been removed, it is necessary to operate the master controller 28 from its switching position to a running position. Move merit of the controller 28 to a running position.

effects closure of the contacts H8 and I28 by occupies the position shown -o the ioning contactor 20 to the negative source of control energy.

Immediately upon closure of the cushioning contactor 30, an energizing circuit is established for the winding II of the operating device 24, which circuit may be traced from the intersection of the previously energized conductors 202 and 203 by way or the interlock contact 204 on the cushioning contactor 30, the conductors 205, 206, I60, I01, and IE8, the interlock contacts i853 on the transfer switch 39 and by way of the conductors I10 and Ill to the energizing winding Ii. In order to ensure that the winding II is energized, even though the cushioning cont-actor 30 fails to close, a parallel energizing circuit is established which by-passes the interlock 204 on the cush" ioning contactor. This parallel circuit may be traced from the intersection of the conductors 20I and 202 through the conductors 201 and 200, the contacts I20 on the master controller 20 and by way of the conductors 209 and M0 to the conductor I61 from which point the energizing circuit is identical with the circuit just traced.

As soon as the winding TI is energized, pressure is applied to the timing chamber i3 so as to operate pistons 65 and lit oi the operating device 24 in a direction to move the brush arm iii of the controller 25 from its A position to its B posi tion so as progressively to exclude the resistor ill from the motor circuit. The operotino device will operate at its high speed due to the loci; that the speed coil 04 is now energioeiii. Tilt: eoeri'i ing circuit for this speed coil may the intersection of the previou ductors 200 and 2I0 through the switch arm I05 on the not which now engages its front doctor 2 I2, the normally olosi braking controller 20 and by "Wttjii i 2I0 through the speed coil iii source of control energy.

As the brush arm iii moves i sition toward its B positli'in, relay 21 operates to control the ope crating device 20 so as to ill tially constant accelerating c the motor current is below a iflie etc the accelerating relay iii occupies i; shown to energize the speed c il t l crating device 24. As soon ti o rent increases above a prod ever, the resulting energi it winding 0 will eiIeot rncv of. the I. i ture I04 so as to disengage contact iii if. the front contact I00, "whereupon the spe 84 is deenergized and the operating device slowed down so as to drive e hrusii arm at its normal or low speed. ilxder these com tions, both the speed coil ti l till the i 80 are deenergized and occur y the which corresponds to normal or over of the operating device 24 and the low If the motor current continues t the armature I04 on the ecceic will be further operated so as movable contact I05 with tacit thereby establish an energieii. stop coil 03 on the device it. circuit extends from the pivoted "out the accelerating relay through the hee I01, the shunt winding ill on the acetic relay and by way of the conductors iii and I16 through the stop coil 03 to the negative source oi control energy. .llloeigi'ioitiri of the stop coil 03 is of course effective to close the valve 11 and stop the operating device 24 and the brush arm 6| of the controller 25.

It has been i'ounrl that if the operating device 24 is thus stopped and held by the stop coil until the motor current drops to such a value that the series winding I09 or the accelerating relay releases the armature ill for movement to disengage the pivoted contact 105 from the back contact M1, the brush arm Bl will move forward in a series oi steps of such duration as to cause the motor current to undergo rather severe fluctuations. Accordingly, the shunt coil ion the accelerating relay 21 is arranged as shown to oppose the series wind ing I 00 and cause the energizing cult for the stop coil 03 to be interrupted il'l'ihic it is closed. Thus, by connecting shunt coil ii I for energization simultaneously on ii. the stop coil 02, a vibrating characteristic is obtained which causes a very slow movement oi the brush arm 6i, depending upon the time that the contacts I05 and i0! remain closed. 'ili ii a very heavy current flows in the circuit the contacts I05 and i0l remain closed a greater portion of the time and a very slow 2 ed movement oi the controller is obtained. a somewhat smaller current is flowing, the contacts i05 and iii! will he closed only a iorlei" portion of the time and accordingly a higher controller speed Will he obtained. it will he not tend oi course that in each. case the controller el is less than th normal slow speed.

5 will oiiserved that the controller re roaster con- .e running coimections actor I. on which i V. since the is in its w it conductor iii e contacts to on switch iii, now closed,

uctoro tit hint til, en. lay any oi the Winding oi the trons-tor switch 0'! negative source oi control energy.

or operation oi the transfer switch 35 to pemnost position, the previously traced encircuit for winding ii of the operatdevice it is interrupted at the interlock con,- toc'ts I08 and accordingly the valves 00 and T0 :oiove to their hissed positions, shown, so as to apply pressure to the piston 65 and connect the timing chamber 73 to atmosphere, thereby to eil'ect operation of the pistons Hi5 and 6B in a reverse direction so as to move the brush arm iii oi the controller 25 from its B position toward its A position. It will likewise be observed that the interlock contacts I94 on the transfer switch 39 open to interrupt the energizing circuit for the valve 45 of the field shunting means 23. This valve Bis maintained energized,however,through a circuit by-passing the interlock contacts I94.

which circuit extends from the intersection of the conductors Hi2 and I93 through a conductor M5, the contacts 88 on the cam switch 26, which contacts are now closed, and by way of the con ductor 220 to the conductor iiiii which extends to the operating winding of the valve, 45.

Movement of the brush arm 6i from its B'position to its A position is effective progressively to exclude the resistor I B from the motor circuit and when the brush arm reaches its A position, the connections shown in Fig. 5 are established, all of the resistors beingexcluded from the motor circuit. As soon as the brush arm 6i reaches its A position, the contacts 83 on the cam switch 26 open to deenergize the operating winding for the valve 46 on the field shunting means 23 and accordingly the valve t5 operates to its biased position shown to connect the upper side of the di aphragm 52 to atmosphere, as described above. Therefore, the spring it forces the plunger 4-3 upwardly and operates the conducting segments til and st into sequential engagement with the contacts 62 and progressively to shunt the field windings of. the motors.

The speed at which the plunger fill operates to shunt the motor fields is controlled by the accelerating relay 275 in a manner similar to that in which the operating device 26 is controlled. lit will be observed that whenever the movable contact wt of the accelerating relay engages the baclr contact till, an energizing circuit is completed for the operating winding of the plug valve 5%, which circuit extends from the heels contact it? through a conductor 22!], the interlocir contacts on the braking switch t t, and by way of a conductor through the operating winding of the plug valve to the negative source of control energy. As described above, energizaticn of the plug valve 583 restricts the exhaust passageway to and accordingly slows down the movement of the plunger tit, and it will be understood that the shunt coil iii cooperates wlth the energizing winding of the plug valve 58 in the same manner as it cooperates with the stop coil ill! on the operating device 2% to provide a vibratory action, the shunt winding ill being energized in parallel circuit relation with the operating winding of the plug valve fit through the previously traced energizing circuit for the stop coil Fig. 6 illustrates the final circuit connections for accelerating the motors, all of the resistance being excluded from the motor circuit, and the fields being shunted.

It will be remembered that the energizing circuit for the transfer switch 39 includes the contacts 85 and 855 on the cam switch 26. In order to maintain the transfer switch in its uppermost position when the cam switch 2% and the brush arm iii return to their respective A positions, a holding circuit is provided for icy-passing the contacts 85 and 86. This holding circuit, which is completed only when both the cushion ing contactor 3t and the transfer switch 39 are in their respective energized positions, extends from the previously energized conductor it! through the interlock contacts 250 on the transfer switch 39, the conductors HI, 24 4, and 252, the interlock contacts 253 on the cushioning contactor 38, and by way of the conductors 254 and M9 to the energizing winding of the transfer switch 39 and a very high value.

the negative source of control energy. Thus the circuits shown in Fig. 6 are maintained until the master controller 28 is returned to its switching position.

It will be understood of course that the com-- plete acceleratingcycle just described takes place in a comparatively short time and accordingly the circuit connections shown in Fig. 6 are established before the speed of the car has assumed After this final circuit is established, the car continues to accelerate, the final 'maximum speed being determined by the load and the grade conditions.

It will now be assumed that the vehicle is operating at a high rate of speed, say for example 40 miles per hour, and that it is desired to initiate braking at this speed. Accordingly, the master controller 28 is operated to its off position to open the contacts H6, Ill, H53, and i2i] and thereby interrupt the energizing circuits for the line breakers 3i); and 3|, as well as the energizing circuits for the cushioning contactor 3i! and the transfer switch 39. Simultaneously, the

series generators to establish dynamic braking,

were it not for the fact that the fields are shunted. Therefore, in order to initiate braking, it is necessary only to operate the braking controller 29 from its oil position to its service position, which operation is effective to complete an energizing circuit for the operating winding of the valve 35 on the field shunting means and unshunt the fields.

This energizing circuit for the operating wind ing of the valve 35 may be traced from the positive source of control energy through the control switch E52, the conductors the, ill, and lit, the switch H26 which is now operated to its up permost position by the associated cam on the braking controller, the conductors 2% and the interlock contacts list, the conductor till, the interlock contacts l58,'the conductors use and N2, the interlock contacts its and M2 on the braking switch 34, the conductors Hit and 225, the contacts I23 on the braking controller, and by way of the conductors 22d and Ito to the operating winding of the valve fit.

It will be remembered that the operating winding H of the operating device 2 1 is energ zed through a circuit which includes the interlock contacts M8 on the transfer switch 39 and since movement of the braking controller 29 to its controller 29, is open at the contacts i2l. As

the brush arm iii of the controller 25 moves toward its B position, the relay 21 operates to control the speed of the device 24 and the brush arm 6|, the series winding I09 01 the relay 2! being connected in the braking circuit, as shown in Fig. '7. Whenever the braking current exceeds a predetermined value, the back contact l0! on the relay 2'! is engaged by the movable contact 105 to energize the stop coil 83, as described above, and thus control the speed of operation of the brush arm 6|.

When the brush arm Bl reaches its B position, the resistor I8 is entirely excluded from the braking circuit, as shown in Fig. 8, and the transfer switch 39 will be energized by closure of the switches 85 and B6 on the cam switch 25, the circuit now extending from the energised inter lock contact I64 through the conductors I55, 206 and HG, the switches 85 and 8B and the con ductors 2I8 and 2H) to the energizing winding of the transfer switch 33. 'Ii'hus the resistor is will be excluded from the braking circuit and the resistor 18 will he reinserted in the hraking circuit, as shown in Fig.

It will be observed that when the transfer switch 39 is operated to its uppermost position, a small auxiliary relay 227 is moved to its closed circuit position by a finger 223 carried on the transfer switch, the relay 221 thereupon sealing itself closed through a circuit which may be traced from the previously energized interlock contact I63 on the braking switch B l through a cooperating interlock contact Milo, the conductors 229 and 230, the winding on the relay ml, the contacts of the relay 221, and or way of the cone ductors 2:, 232, 201, 202, Hi3, and the energizing winding of the cushioning contactor to the negative source c ntrol energy.

It will thus he that no 34 closed, open o to its uppermost o the 35 is in erlccli: comm o icning contactt oration to its it "wi l i zprior to energization of the cushioning con ,ctor, since the cushioning contactor, once has hcen oner ates to its closed circuit position, not niiectetl by operation of the interlock lever Mil.

As described above in. connection with the ac cclerating operation, inct'eir t of the transfer switch 39 to its upoerrncet 1 ion interrupts the energizing circuit for the illiilllfi "ii the in 'terlock contacts its antl'occortiinglr the brush arm Bl immediately starts to move from. its is position toward its A position again to exclude the resistor ill from the braking circuit. i soon as the brush arm 8] reaches its it position, the contacts 86 on the cam switch 26 open to tleenergize the transfer switch 39, whereupon the transfer switch moves to its lowermost position to reinsert the resistors l8 and iii in the motor circuit, as shown in Fig. 10, It will be remembered that the initial energizing circuit for the transfer switch 39 includes the contacts 85 and 86 on the cam switch 26. Although the contacts 85 open as soon as the cam switch 25 moves from its B position, the energizing circuit is maintained, until the cam switch reaches its A position and the contacts 86 open, by means of a by-pass circuit which may be traced from the intersection oi the conductors I65 and 206 in the previously traced energizing circuit through the conductors I66 and 167, the interlock contacts 258 on the transfer switch 39 and by way of the conductors 25i and 245 to the contacts 8!).

Immediately upon operation of the transfer switch 39 to its lowermost position, the interlock lever 235i releases the previously energized cushioning contactor 38 for movement to its closed circuit position to exclude the resistor 29 from the braking circuit and accordingly the circuit connections shown in Fig. 10 are established. At the same time, the cushioning contactor 3t seals itself in through the interlock contacts 204, which contacts establish a short circuit around the energizing ti intiing oi the auxiliary relay 221 to permit the relay to open. This short circuit extends from the intersection of the conductors M52 and 203 in the energizing circuit of the relay 221 through the interlock contacts Film, the conductors M15, iillii, and H35, and by Way of the interloci: contact iii i to the interlock contact 223s in the previoush traced energizing circuit oi the relay 227.

Upon operation oi the transfer switch 39 to its 30 lowermost position, the winding l i oi the oneratinc; device i l again energized .ough the interlock contacts iliii oi the tran itch and accordingly ti crush arni ti controller 25 is o1 from toward its B 35 position to exclude circuit third tilt soon as the hr ltnl iii the sol uh 1" this ii oi; ncctlttlncly the hole no t 1 connection with the ncceler us the con goosrion, not; oneratetl to lnte will he well understood in? those skilled in art, elicited traction motors will not huilcl up series generators unless the external resistance connected in "the armature circuits is less than a critical resistance, which critical resistance depends upon the speed at which the motors are driven. In the above described braking operation, it was assumed that the vehicle "was operating at a high rate of speed, for example 40 miles per hour, and since the sum of the resistors l8, 19, 2D, and 2! isless than the critical resistance of the traction motors at this speed, the motors build up toestablish dynamic braking as soon as the braking controller is operated to remove the field shunts. If, however, the vehicle is operated at a lower speed, it will be seen that unless special provision is made a considerable time interval will elapse between operation of the braking controller and the time that the motors build up as series generators due to the fact that the controller must move through a portion of its cycle to exclude a portion of the resistance in the braking circuit, depending upon the speed at which the vehicle is operated. In order to ensure that braking will be established immediately upon operation of the braking controller at all speeds, the spotting relay 40 is provided for operating the controller 25 during coasting to predetermine the resistance included in the braking circuit upon operation of the braking controller.

As briefly described above, the spotting relay 40 is provided with a winding I00 connected for energization in accordance with the speed of the traction motors to operate a cam 94 which cooperates with the winding I03 to control the contact 92, the conducting finger 98 and the latch I02. Upon operation of the master controller 28 from its off position to its switching position, a circuit is established for connecting the energizing winding I00 across the motor fields I4 and I5 so as to energize the winding I00 in accordance with the speed of the motors and upon operation of the controller 29 to its running position, an energizing circuit is established for the winding I03 so as to release the cam disk 94 for movement in accordance with the energization of the winding I00.

The energizing circuit for the winding I00 extends from the right-hand terminal of the field winding I4 through the conductor I21, 9. conductor 236, the winding I00, a conductor 231, a pair of interlock contacts 239 on the line breaker 3|, and by way of the conductors 239 and I48 to the left-hand terminal of the field winding I5. Likewise, the energizing circuit for the winding I03 extends from the contacts II9 which are closed when the controller 20 is in its running position through the conductors I99 and 240 by way of the winding I03 to the negative source of control.-

energy. As soon as the winding I03 is energized to release the latch I02, the cam disk 94 is moved to its extreme right-hand position against the bias of the spring 99, the inductive kick which occurs upon initial energization of the field windings I4 and I5 being sufilcient to cause operation of the cam disk 94 to this position as soon as it is released.

The cam disk 94 is maintained in this extreme right-hand or low speed position during the complete accelerating cycle which, as described above, takes place in a comparatively short time. As soon as the circuit connections shown in Fig. 6 are established, the field windings being shunted,

- the cam disk 94 begins to move back toward its left-hand or high speed position as the speed of the motors increases, the winding I00 being so related to the field windings I4 and I5 that movement of the disk 94 is a direct measure of the motor speed. 1

If the vehicle attains its high rate of speed before it is desired to initiate braking, the cam disk 94 will occupy the position showrrand the braking operation will take place as described above. If, however, it is desired to initiate braking with the vehicle operated at a somewhat lower rate of speed, say 35 miles per hour, the cam disk 94 will occupy a position slightly to the right of that shown and accordingly when the master controller 28 is returned to its off position, the cam disk 94 will be latched in a position such that the finger 98 comes to rest part way up the cam surface 95 when thewinding I03 is deenergized by opening of the contacts I20.

With the cam disk 94 latched in this position, it will be seen that the contacts 9| and 92 are separated a short distance and accordingly the previously traced energizing circuit for the stop coil 83 on the operating device 24 is interrupted. Therefore, as soon as the master controller 20 is operated to its off position, the operating device 24 begins to move the controller 25 so that the brush arm 6i moves toward its B position. This movement of the brush arm Iii toward its B position continues until the contact 9i, operated by the cam 89 on the cam switch 26, engages the contact 92 to energize the stop coil 83. Thus a portion of the resistor I8 will be excluded from the braking circuit during the coasting operation and as soon as the braking controller 29 is operated to its service position to unshunt the motor fields, the braking current will immediately build up. As mentioned above, the operation of the braking controller to its service position also interrupts at the contacts I22 the energizing circuit for the stop coil 93, which, circuit extends through the contacts 9I and 92, leaving the stop coil 03 under the control of the relay 21. Therefore, the brush arm BI immediately begins mov ing again toward the B position and the remainder of the braking operation is carried out as described above.

If the vehicle is operating at a still lower speed, say 30 miles per hour, when it is desired to initiate braking, the cam disk 94 will be still further to the right when latched upon operation of the controller 28 to its off position and accordingly the conducting finger 98 will come to rest in the apex of the notch between the cam surfaces 95 and 96 in engagement with the conducting surface 98. Since the contacts 9i and 92 are separated, the operating device 24 immediately begins to move the brush arm 6| from its A position toward its B position and as soon as the contacts 06 on the cam switch 26 close, an energizing circuit is established for the transfer switch 39, which circuit may be traced from the previously energized interlock contact 228a on the braking switch 34 through the conductors 229 and MI, the conducting finger 90, the conducting segment 96,-a conductor, 242, the interlock contacts 240 on the cushioning contactor 38, the conductors 244 and 245, the contacts 06, the conductors 2I0 and 2I9, and by way of the energizing winding of the transfer switch 39 to the negative source of control energy. Thus the transfer switch 39 is operated to its uppermost position and the brush arm 8| continues to operate until it reaches its B position in which position the contact 9i engages the contact 92 so as to stop the brush arm 9|. Thus the circuit connections shown in Fig. 9 are established.

It will be remembered that operation of the transfer switch 59 to its uppermost position during either accelerating or braking is effective to deenergize the winding II on the operating device 24. During coasting, however, a by-pass circuit is established which maintains the winding 'II energized regardless of the position of the transfer switch 39, this by-pass circuit being traceable from the previously energized interlock contact II! on the braking switch 24 through the similar interlock contact I12, the conductors I'll and 22!, the contacts I24 which are closed when the braking controller 28 is in its oil position, a conductor 2, the interlock contacts 2" on the -braking switch 24, andby way of the conductors 2" and ill to the winding H. As soon as the braking controller 29 is operated to its service position to unshunt the fields and initiate braking, as described above, the energizin: circuit Just traced tor the winding H or the operating device 24 is, interrupted at the contacts I24 and since the transfer switch 39 is in its uppermost position, the operating device immediately begins to move the brush arm BI from its B position. toward its A position, the re mainder of the braking cycle thereupon being carried out as described above.

It the vehicle is operating at a still lower speed, say, 25 miles per hour, the spotting relay" will operate exactly as described amve except that the conducting linger 88 comes to rest hali way down the conducting surface 93 and. accordingly, the contacts 80 and M will be closed when the brush arm GI reaches a position midway between its A and B positions. Thus, the remainder of the circuit connections being as shown in Fig. 9. braking is initiated with all of the resistor l9 and hall. of the resistor i8 excluded from the braking circuit.

At a speed 01' approximately 20 miles per hour, the cam disk 94 is latched in such a position that the conducting linger 98 engages the conducting surface 91 adjacent its crest. In this position, the contacts 9i and 82 are maintained closed and accordingly, the brush arm 6| remains in its A position. An energizing circuit is completed, however, which immediately effects closure of the cushioning contactor 38 so as to establish the circuit connections shown in Fig. 10. This ener gizing circuit for the cushioning contactor 38 extends from the conducting finger 98 through the conducting segment 81 and by way of the conductors 248, 232, 201, 202, and 203 to the energizing winding of the cushioning contactor 3|. Thus, as soon as the braking controller 29 is operated to unshunt the fields and to interrupt at the contacts I22 the energizing circuit for the stop coil 83, the brush arm 6i begins to move from its A position toward its B position and the remainder of the braking cycle is carried out, as described above. The same operation occurs ii braking is initiated with a vehicle operating at a. speed of 15 miles per hour except that the con ducting finger 98 comes to rest half way up the conducting surface 91. Under these conditions, the contacts 9| and 82 are opened and the brush arm ll moves toward its B position until these contacts are engaged. Thus, the circuit connec tions established prior to braking are identical with those shown in Fig. 10 except that half oi the resistor 18 is excluded from the braking" cir cult.

I! braking is initiated at a still lower speed. say 10 miles per hour, the cam diell'. t4 oi'icupies its extreme right-hand cocition, the contact ger 98 coming to rest at time uppermost end conducting surface 91. Thus, the cucliior .ig contactor 38 is immediately energised, as scribed above, and the brush arm 6i moves all the way to its B position before the contacts at and 92 close. As soon as the brush arm 8! reaches its B position, the transfer switch 39 is energized through closure oi. the contacts on the cam switch 28 and accordingly the circuit connections shown in Fig. 11 are established.

It will now be. apparent that the spotting operation which predetermines the resistance initially included in the braking circuit is quickly accom- 6 plished at low speeds without waiting for the brush arm 8| to move through two or three trips by arranging the conducting segments 98 and 91, as described above. With this arrangement, spotting is accomplished by moving the brush arm through a maximum of one trip between its A and B positions.

It is sometimes desirable, after braking has been established, to permit the vehicle to coast for a short time and then to reestablish the i5 braking. In order that the braking circuits may on oi the "cg one whirled with an .c .i moi c. till. he soon s an appreciable braking current lion s through the resistor 2 l, the winding 255 is energized to move the miniature 93 and release the latch Hill on the spotting relay. Since the energizing winding Hill is deenergized, its circuit being interrupted at the inter lock contacts 233 on the line breaker 31, the cam disk 94. immediately moves to its extreme leithand or biased position shown. In this position the contacts BI and 92 are maintained closed at all times regardless of the position of' the brush arm 6! and the cam switch 26 and accordingly as soon as the braking controller 29 is operated to its off position, the stop coil 83 of the operat ing device is energized to stop the brush arm 6| in the position it then occupies. Operation of the braking controller to its off position is eil'ective to kill the braking action since the operating winding of the valve :15 on the hold shunting means 23 is deenerglzed by opening 01 the contacts I23 on the braking controller so as to shunt the motor fields. Reestablishment oi the braking current may thus be accomplished simply by returning the controller to a service posi tlon to unshunt the fields.

While I have described in some detail the seam plete control system in order to facilitate a coinnlete understanding of my invei'ition, it should he understood that no claim is herein made to the specific spotting means shown, nor to the lie-- tailed arrangement of the shunt coil lil the accelerating and decelerating relay 2?, these and certain other features being fully described claimed in a copending application, lz'ieriol i. Home, iiled April iii, will, by Jacob W. ivi'cittliiy and me, which application assigned to ccsignee as the present invent fill ly the iii-airing operctioi.

c t lecture iilei'iol l lo. i plicai .t inven on.

we a nl;

cot

t, i. that if do not mall to limited thereto many modifications may be made and ii, therespirit and scope of my invention. 7

What I claim as new and desire to secure by Letters Patent the United States, is:

1. In a control system, a plurality of resistors, a controller for varying one of said resistors, switch mechanism for connecting said resistors in a control circuit with each other for exclusion of said one resistor from said circuit by move- I to ment of said controller in one direction and for connecting said one resistor in said control circuit alone for exclusion from said circuit or said one resistor by return movement of said controller.

2. In a control system, a fixed resistor, a variable resistor, contact mechanism movable in either of two directions for varying said variable resistor, connections connecting one end of one of said resistors to one end of the other of said resistors, connections for connecting said contact mechanism ina control circuit, switching mechanism for connecting the other end of said fixed resistor in said control circuit for exclusion from said circuit of said variable resistor by movement of said contact mechanism in one direction and for connecting the other end of said variable resistor in' said control circuit for exclusion from said circuit of said variable resistor by return movement of said contact mechanism.

3. In a control system a fixed resistor, a variable resistor, contact mechanism movable in either of two directions for varying said variable resistor, connections for connecting one end of one of said resistors to one end of the other of said resistors, connections for connecting said contact mechanism in a control circuit, and a two way switch movable to one position to connect the other end of said fixed resistor in said control circuit for exclusion from said circuit oi said variable resistor by movement of said contact mechanism in; one direction and to another position to connect the other end of said variable resistor in said control circuit for exclusion from said circuit of said variable resistor by return movement of said contact mechanism.

4. In a control system a pair of motor controlling resistors, a controller for varying one of said resistors, switch mechanism movable to a first position to connect said resistors in a control circuit with each other for exclusion from said circuit of said one resistor by movement of said controller in one direction and movable to a second position to connect said one resistor in said control circuit alone for exclusion from said circuit of said one resistor by return movement of said controller, a third resistor for connection in said circuit, and means for excluding said third resistor from said circuit and for returning said switch mechanism to said first position.

5. In a control system a fixed resistor, a variable resistor, contact mechanism movable in either of two directions for varying said variable resistor, connections for connecting one end of one of said resistors to one end of the other of said resisters, connections for connecting said contact mechanism in a control circuit, and a switch movable to a first position to connect the other end of said fixed resistor in said control circuit for exclusion of said variable resistor from said circuit by movement of said contact mechanism in one direction and to a second position to connect the other end of said variable resistor in said control circuit for exclusion of said variable resistor from said circuit by return movement of said contact mechanism, a second fixed resistor for connection in said control circuit, and means for excluding said second fixed-'resistor from said circult and for returning said switch to said first position to reinsert in said circuit said first fixed resistor and said variable resistor.

6. In a motor control system, a plurality of motor controlling resistors for connection in circuit with a motor, a controller associated with one of said resistors, means for operating said controller in one direction to exclude said one resistor from said motor circuit, means responsive to said operation of said controller for excluding another of said resistors and for reinserting said one resistor in said motor circuit, and means including said operating means for operating said controller in a reverse direction to exclude said one resistor from said motor circuit a second time.

7. In a motor control system, a plurality of motor controlling resistors for connection in circuit with a motor, a controller associated with one of said resistors, means for operating said controller in one direction progressively to exclude said one resistor from the motor circuit, means responsive to said operation of said controller for quickly excluding another of said resistors and for reinserting said one resistor in the motor circuit, means including said operating means for operating-said controller in a reverse direction progressively to exclude said resistor from the motor circuit a second time, and means responsive to the current in the motor circuit for governing the speed of said operating means in both directions.

8. In a motor control system, the combination of an electric motor, a plurality of motor controlling resistors, means for connecting said resistors in circuit with said motor, a controller associated with one or said resistors, means for operating said controller from one position to a second position to exclude said one resistor from said motor circuit, transfer means operable when said controller reaches said second position for excluding a second one of said resistors and for reinserting' said one resistor in said motor circuit, and means including said operating means responsive to operation of said transfer means for reversely operating said controller from said second position to said one position progressively to exclude said one resistor from said motor circuit a second time.

9. In a motor control system, the combination of an electric motor, a plurality of motor controlling resistors, means for connecting said resistors in circuit with said motor, a controller associated with one of said resistors, a fiuid operator for said controller, control means for effecting operation of said fiuid operator in one direction thereby to move said controller from one position to a second position progressively to exclude said one resistor from said motor circuit, transfer means operable when said controller reaches said second position for excluding a second one of said resistors and for reinserting said one resistor in said motor circuit, and means responsive to operation of said transfer means for influencing said control means to effect reverse operation of said fluid operator thereby to move said controller from said second position to said one position progressively to exclude said one resistor from said motor resistor troller to another position for quickly excluding said third resistor from said circuit, an acceleration controller associated with one of said pair of resistors, means responsive to operation of said switch means for operating said acceleration controller in one direction progressively to exclude said one resistor from said circuit, transfer means responsive to said operation of said acceleration controller for quickly excluding the second resistor of said pair and for reinserting said one resistor in said circuit, and means including said operating means responsive to operation of said transfer means for operating said acceleration controller in a reverse direction progressively to exclude said one resistor from said circuit a second time.

11. In a motor control system, a plurality of motor controlling resistors ior connection in circult with a motor, a controller associated with one of said resistors, a reciprocating fluid pressure operating device having opposing pistons each for operating said controller in a corresponding direction, timing .means comprising a chamher having an incompressible iiuid therein, nor mally open valve means controlling the flow oi said fluid ior establishing communication icetween said chamber and one of said pistons, valve mechanism for selectively admitting pressure either to said chamber or to the other of said pistons to effect timed operation 01' said controller in a corresponding direction, means for controlling said valve mechanism to attract operation of said controller in one direction progressively to exclude said one resistor from said circuit, transfer means responsive to said one said controller ior excluding another or sisters and lot r user-ting cold one res said circuit, mean to opcrat transfer means ior ariisni to oil reverse till or for opening iurtl'ier means to increase ilie spect controller.

12, In a motor control or" of an electric motor, ,1 trolling resistors connec motor, a controller use resistors, a reciprocating llill device having opposing pinto each for or lg said controller in a correspo: ng direction, tiin-- ing means comprising a clip her having an compressible iiuid therein, normally open valve means controlling the flow of said fluid for Qilllillfl llshing communication between said chamber and one of said pistons, valve mechanism for selec tively admitting pressure either to said chamber or to the other or said pistons to effect timed op eration of said controller in a corresponding direction, means for controlling said valve mech anism to effect operation or said controller in one direction progressively to exclude said one resistor from said motor circuit, transfer means responsive to said operation of said controller for can eluding another oi said resistors and for rein-- serting said one resistor in said motor circuit, means responsive 'to operation of said transfer means for controlling said valve mechanism to eflect operation of said controller in a reverse direction progressively to exclude said one resistor from said motor circuit a second time, current responsive means for selectively closing said ally open valve .o. operation ti with one occasion ope normally open valve means to stop said controller or for opening further said normally open valve means to increase the speed of operation of said controller whereby a substantially constant motor current is obtained, and means for adjusting the current setting of said current responsive means.

13. In combination, a circuit controller selectively operable in two directions through a series of circuit controlling positions, a reciprocating fluid pressure operating device therefor having opposing pistons each for operating said controller in a corresponding direction, timing means comprising a chamber having an incompressible fluid therein in communication through a restricted orifice with one of said pistons, valve mechanism for selectively admitting pressure either to said chamber or to the other oi said pistons to effect timed operation of said controller in a corresponding direction, and means responsive to an electrical condition of circuit for selectively closing said restricted orifice to stop said controller or for enlarging said oriilce to increase the speed of said controller.

14. In combination, a circuit controller seleclively operalsle in two directions through a series oi circuit controlling positions, a reciprocating irluid pressure operating device there-for having opposing pistons each for operating said circuit controller in a corresponding direction, timing means comprising a chamber having an incompressiiole fluid therein, normally open valve means ior establishing communication lie-tween said cliamlier and one oi said pistons, valve mecha" isi'n for selectively admitting press-l "e either to stori to e col timed no to iricrei o controller. coinioina elv o erwole in having v open valve n us to cl controller in it corrcsoont i it responsive menus for sole rllgv open valve means to ste e or ior opening iurtlier said valve crease time speed of said. controller stuntinllv constant cantor current and means for adjusting the rent o onsive means.

litlin a motor control ii /"stern motor controlling resistors ior co said second resistors for progressive exclusion during succeeding forward and return trips 01' said controller.

17. In a motor control system, a plurality of motor controlling resistors connected in circuit with a motor, a controller, means for selectively operating said controller through forward and return trips between two positions to control the progressive exclusion of a first .one of said resistors from the motor circuit, transfer means second resistors and for controlling said switch means to exclude said third resistor, and means responsive to operation of said switch means for controlling said operating means again to effect a forward trip of said controller progressively to exclude said resistor a third time, said transfer means again operating at the completion of the forward trip to exclude said second resistor and to reinsert said first resistor for exclusion a fourth time during return movement of said controller.

iii. In a motor control system, the combination of an electric motor, a plurality of motor controlling resistors for connection in circuit with said motor, transfer means for controlling the connections of two of said resistors, a controller sequentially operable through forward and return trips between two positions for controlling a first one of said two resistors, said transfer means being responsive to the progressive exclusion of said first resistor irorn the motor circuit during a forward trip of said controller for excluding the second one or said two resistors and reinserting said first resistor for progressive exclusion a second time during the return trip of said controller, switch means for controlling the inclusion and exclusion of a third one of said resistors, master control means for selectively connecting said motor and said resistors in ac-' celerating or braking circuits, means respon sive to establishment of said accelerating circuits for first effecting operation of said switch means to exclude said third resistor and for then effecting operation of said controller through said two trips progressively to exclude said two resistors, and means responsive to establishment of said braking circuits for eiIecting progressive exclusion of said three resistors by operating said controller through four trips, said switch means and said transfer means cooperating at the end of the second trip of said controller to exclude said third resistor and to reinsert said two resistors for progressive exclusion a second time during the succeeding two trips of said controller.

19. In a motor control system, a plurality of motor controlling resistors, means for connecting said resistors in acceleration and braking circuits with a motor for acceleration and braking of the motor, a controller operable through predetermined forward and return trips progressively to exclude a first one of said resistors, means for reinserting said first resistor in the motor circuit in place of a second resistor at the completion of each forward trip of said controller, means for operating said controller through two trips progressively to exclude said first and second resistors from the motor circuit during acceleration, and means for operat ing said controller through four trips during braking, said last mentioned means including means for reinserting said first and said second resistors in said braking circuit in place of a third resistor upon completion of said second trip whereby said three resistors are progressively excluded from said braking circuit during said four trips of said controller.

20. In a motor control system having an electric motor, a motor controlling resistor, and control means for progressively excluding said resistor from the motor circuit, the combination of master control means for selectively connecting said motor and said resistor for acceleration or for dynamic braking, said master control means including separately operable braking and accelerating controllers, relay means having an armature movable from one position to another position for controlling the speed of operation of said resistor control means, spring means biasing said armature to said one position, means for energizing said relay meansin accordance with the motor current during both braking and acceleration, whereby said relay means controls said resistor control means to maintain substantially constant motor current, and means responsive to operation of either said braking controller or said accelerating controller for adjusting said spring to vary the bias on said armature and the current setting of said relay means.

21. In a motor control system having an electric motor, a motor controlling resistor, a resistor controller, and means for operating said resistor controller progressively to exclude said resistor from the motor circuit, the combination of master control means including separately operable braking and accelerating controllers for selectively connecting said resistor and said motor for acceleration or for dynamic braking, relay means having an armature normally biased to one position and operable to another position to control the speed of said operating means, means for energizing said relay means to operate said armature in accordance with the motor current during both acceleration and braking, whereby a substantially constant motor current is maintained, and cam means responsive to operation of either said braking controller or said accelerating controller for adjusting the bias on said armature to vary the value of the motor current maintained by said relay means.

22. In combination, a motor controller selectively operable in two directions through a series of positions, a reciprocating fiuid pressure operating device therefor having opposing pistons each for operating said circuit controller in a corresponding direction, timing means comprising a chamber having an incompressible fluid therein, normally open valve means for establishing communication between said chamber and one of said pistons, valve mechanism for selectively admitting pressure either to said chamber or to the other of said pistons to effect timed operation of said controller in a corresponding direction, selectively energizable means for opening further said normally open valve means to operate said controller at a high speed or for closing said normally open valve means to stop said controller, relay means normally biased to one position for energizing said selectively energizable means to effect high speed operation of said controller, means energizing said relay in accordance with the motor current for operating said relay to deenerglze said selective means and operate said controller at its normal speed upon the occurrence of predetermined current conditions, and for further operating said relay to energize said selective means to close said valve means and stop said controller upon the occurrence of other predetermined current conditions.

23. In combination, a motor controller selcctively operable in two directions through a series of positions, a reciprocating fluid pressure oper ating device therefor having opposing pistons each for operating said circuit controller in a corresponding direction, timing means compris ing a chamber having an incompressible fluid therein, normally open valve means for estahlishing communication between said chamber and one of said pistons valve mechanism for selec tively admitting pressure either to said chamber or to the other or said pistons to effect timed operation of said controller in a corresponding said controller upon the occurrence of predetevmined current conditions, said relay energizing means eifecting further operation of said movable contact to engage said back contact and energiate said selectively energizanle means to stop said controller upon the occurrence oi other predetermined cnrrent conditions,

JOHN F. TRIITLE. 

